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Sup Fanatics,
At my shop we recently replaced the 1/4 panel on a 2009 BMW 135i. If you saw my "Bumper Job" thread, you may wanna check this out.

Customer was shopping around for the best shop to repair his car (smart man, not shopping for estimates, but shopping shops)

Customer brought us this,

So lets see whats going on under there...

Step 1 strip it down...
Before we start chopping off the damaged 1/4 panel we have to set the car up on our CARBENCH Jigs... (In order to mount the car to Jigs we must loosen/drop/suspend/remove suspension, exhaust, fuel tank as well as misc. under covers etc...)

The Jigs get the car back to factory specs and tolerances up to 2mm (Per BMW)

Once we have it bolted up to the Frame Machine we can remove the glass and begin the sectioning of the 1/4 panel.

Here is our new 1/4 panel (Caged animal )

These are the adhesive kits that get used for bonding the 1/4 panel to the car. Keep in mind, BMW recommends weld bonding their replacement panels rather than the conventional "weld it back together method"

The reason BMW recommends this, not only the corrosion protection it provides, but also this keeps the factory crumple zones and the car will act the same way in future accidents *knock on wood*

I know what you're thinking... GLUE????? but this is structural panel bonding adhesive that has holding properties equal to or greater than welding. By no means is this a cheaper / easier fix. If anything it's more expensive requiring special materials and more time for this procedure...

So here's what we got...

Metal Filler/Puddy
- This is in place of your traditional BONDO :thumbdown
- THIS IS NOT A REGULAR BODY FILLER, this is a metal filler that bonds to the panel producing a stronger bond and a longer lasting bond

Back Glass Adhesive
- Since the windshield and back glass are structural components in our cars, BMW recommends the use of their glass adhesive to maintain factory structural properties.

Glass kit also comes with Primer
- the glass adhesive must be applied to the correct type of primer or else the adhesive could fail or come out with the cheap primer altogether.

1/4 section Back Plates
-these go behind the section areas to create not only a perfect alignment, but also during bonding it becomes another structural component in the 1/4 panel.

Bodywork Adhesive
- this is the expensive stuff that becomes your bonding agent

There is a process involving these glues to get them to bond

Structural Foam
- reduces sound & vibration and also acts as a structural component once dried

Cavity Wax
- This is the same stuff that you see dripping between all your door jambs from the facory.
- once primed and sprayed over by the cavity wax, it creates a corrosion protection barrier.

Unfortunately my tech Toretto pre-fit the 1/4 panel and cut it before I had chance to take my photos. so the test fit photo you'll have to use your imagination.

Once in place with the glue we need to let it sit for 18-24 hours to dry, at the same time my tech is spot welding the flanges to create the "Weld Bond"
once dry and in place we can apply the metal puddy and shape the bonded area to prep it for paint.

Once it's all smooth and pretty, we get it prepped for paint

This is not the booth we paint in, we just left it in the bumper booth over night to prevent moisture

Once the paint is dry we get all the seats back in and the glass and shoot it over to detail where we color sand and buff the painted panels

... and here we spot Turbomike's widebody 335i getting ready & detailed for the track after we just painted the bumper... lol

I appologize that I may have skipped a lot of steps, but I'm doing an F12 now and I plan on taking more photos...

Here's the final product... like it never happened

Come by and check us out if you are in the Los Angeles are and need some work done.

Feel free to contact me directly if you yourself are in a situation and need some body work in So*Cal
Or just swing by and check out the shop if you are in the are and talk cars with us nerds in the office. As a shop we plan on doing more and more Auto X events and future clinics.